Thedunzelmon

Okay ill keep things short because i have been having issues posting to this forum cause im new here. But my 2004 GT is idling funky when warming up. It surges between 700 and 900 rpm. When driving everything is fine no spitting or missing. No engine codes. Just this unusual idle. The car has an aftermarket intake and throttle body which i have checked and everything is on nice and tight. Thottle position sensor is new. I ordered a new IAC valve and am having trouble to find a new PCV valve for my motor. My car has 82000 miles and never did this until recently and i want to fix it before it gets worse. Is there something i didnt check? Something else it could be? Please help

Brad01GT

Not saying this is your issue but I would start with checking the codes and seeing if its having a spark issue, if you can get a good scanner or borrow one, you could see if it misfires in any cylinder or use an oscilloscope to check the coil on plugs. Could just be a misfire, I had the same problem. After doing a spark plug and coil on plug swap, the problem went away. Like I said, my problem could be different from yours.